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NEMA 17 vs NEMA 23: Torque, Speed, and When to Upgrade

When building a CNC router or upgrading a 3D printer, the first question is usually: "Is NEMA 17 enough, or do I need NEMA 23?" Most beginners look at the Holding Torque and stop there. This is a mistake. A NEMA 23 motor isn't just "stronger"—it is physically different in ways that affect your speed, your driver choice, and your machine's ability to avoid missed steps. If you choose a NEMA 17 for a heavy gantry, it is far more likely to overheat or lose steps under cutting load. If you choose NEMA 23 for a fast 3D printer, it might actually run slower than the smaller motor. This guide explains the engineering limits of each frame size. Table of Contents 1. Physical Difference (The Frame Size) 2. Torque & Speed (The Inductance Trap) 3. Driver Compatibility 4. Selection Summary Advertisement 1. Physical Difference (The Frame Size) "NEMA" is just a standard for ...
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NX Motion Simulation: Integrating Excel Timing Diagrams - Part 1

During the process of timing diagram design, I normally start with detailed calculations in an Excel spreadsheet to minimize acceleration while satisfying the required process cycle time.

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Once I can visualize the preferred displacement, velocity, and acceleration profiles of the mechanisms in Excel, the question becomes: What's next? Shall I start manufacturing immediately?

The answer is NO. In modern engineering, we use Digital Twin Technology to verify the design first.

From Excel to 3D Simulation

Currently, I use Unigraphics (UG) NX4 (now Siemens NX) to design the mechanical parts. When the assembly modeling is done, I use the assembly model to simulate the movement of mechanisms with the Motion Simulation Module.

This step is critical for Virtual Commissioning. It helps confirm the timing diagram before releasing the design for manufacturing. It is especially useful when movements are combined in 3D space, allowing me to detect interference (collisions) with other mechanisms and solve them proactively.

The Challenge: ADAMS Functions vs. Excel Data

When I first started using the UG NX4 Motion Simulation Module, I found it easy to set the links and define joints. However, I found it difficult to define the driver functions using ADAMS-General built-in functions.

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These functions are powerful for "Dynamics" environments, but often I prefer "Kinematics" because it's fast and focuses purely on displacement.

Can you imagine how difficult it is to manually write fifth-degree (3-4-5) polynomial cam functions for 3-4 different sectors inside this function editor? It is prone to syntax errors and is tedious to debug.

The Solution: "Spreadsheet Run"

I'm still familiar with using Excel spreadsheets to calculate things. It's easier if I can use the motion table that I've already generated during the design phase.

I finally found out that besides "Animation" and "Articulation", UG NX4 has command features called "Graphing" and "Spreadsheet Run".

These 2 commands allow me to import the Excel data directly to drive the simulation without entering complex functions manually.

The Workflow:
  • Calculate profiles in Excel (Cycloid, Polynomial, Linear).
  • Copy & Paste the values into the NX Spreadsheet Run tool.
  • Visualize the 3D motion instantly.

If the timing diagram is wrong, I just modify it in Excel and re-paste. This rapid iteration is the core of Computer-Aided Engineering (CAE).

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